METHODS OF DETERMINING LITHOLOGICAL CHARACTERISTICS OF AN UNDERGROUND FORMATION WHICH UTILIZE COMPRESSIONAL VELOCITY

摘要

ABSTRACTMethods and related apparatus are described fordetermining lithological characteristics, such as forma-tion material type and porosity, of an underground forma-tion by utilizing compressional velocity (Vp) and shearvelocity (Vs) data. One described method utilizes theplotting of Vp and/or Vs versus a Seismic Parameter, suchas K/p or the Bulk Velocity, and boundaries of velocityvalues of certain formation material types to define afield of data points. By comparing the position of thedata points to the boundaries of the formation materialtypes, the formation material type and, later, porositycan be determined. A method is described for determiningthe presence of a hydrocarbon gas at a particular locationin an underground formation utilizing the above methods.Also, a method is described for determining Vs from Vpdata and obtained ratios of Vp and Vs for at least oneformation material type.